Flexible electrical conduit.



WITNESSESI W. C. ROBINSON.

FLEXIBLE ELECTRICAL CONDUIT.

APPLICTION FILED JUNE 3. 1912.

Patented Nov. 7, 1916.

NTOR

UNITED STATES PATENT oEEIcE.

WILLIAM C. ROBINSON, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO NATIONALMETAL MOLDING COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION 0FPENNSYLVANIA.

FLEXIBLE ELECTRICAL CONDUIT.

Specification of Letters Patent.

Patented Nov. 7, 1916.

Application led June 3, 1912. Serial No. 701,315.

To all whom t may concern Be it known that I, WILLIAM C. ROBINSON,residing at Pittsburgh, in the county of A1- legheny and State ofPennsylvania, a citizen of the United States, have invented ordiscovered certain new and useful Improvements in Flexible ElectricalConduits, of which improvements the following is a specification.

The present invention is an improvement upon that described in UnitedStates Letters Patent No. 652,806.

In the accompanying .drawings Figure 1 is a View, partlyl in section,of'a section of conduit embodying the invention. Fig. 2 represents (on alarger scale) a strand of paper or like material formed of stripstwisted together. Fig. 3 is a cross-section of the twisted circular'strand on the line III--III of Fig. 2. Fig. 4 includes enlarged views inplan and in cross-section of the flattened strip which is used as thesemiiiexible member of the conduit. y

In order to form the semi-iexible member of the conduit I crumple andtwist together a number of strips of thin paper or a similar material asgenerally indicated at 1 in Fig. 2. A single strip lof paper ofsuiiicient width may be so twisted, and if desired the strip or stripsmay'have appliedp to them an insulating varnish or sizing.

This forms a twisted strand which is circular in cross-section, as shownin Fig. 3. Then I Hatten the twisted strand in any suitable way, as bypassing it between pressure rollers, thus forming a comparatively thinstrip, shown in Fig. 4, which I have found possesses the necessaryfirmness and strength for use in a conduit in the'manner described inthe Letters Patent above referred to. It possesses the advantages overthe helically coiled member Iof the said Letters Patent, that whilequite rm and strong, it is also relatively thin and of light weight.Having formed this semi-iexible strip 1, I proceedto coil. it helicallyas shown in Fig. 1 of the accompanying drawings, and then interweavewith said strip strands 2 of thread, yarn or any similar fiexibleInat`erial.

I claim as my invention:

A conduit consisting of a helix formed of a Hat strand of twisted paper,in combination with flexible material interwoven therewith.

v "In testimony whereof I have hereunto set my hand.

WILLIAM o. ROBINSON.

Witnesses: c FRANCIS J. ToMAssoN, 'J. HERBERT BRADLEY.

